Catch 22 with transmission fluid change?

[Erin]

In my acura that is about to hit 265,000 miles, the fluid is dark red brownish, but not burnt to a black crisp like some of the units I saw come through the shop many years ago. I drew out a couple tablespoons to get an honest idea of it’s condition.
So, thinking it may need changed.

It is pretty well established that “flushing” a trans is likely to cause problems if the car has high miles. I would not dream of doing that.

But now here are a couple problems with changing fluid when the service history is unknown…
Let us assume you are just doing a “pan drop”.

If you do NOT change the fluid, you risk failure due to the fluid going to crap.
If you DO change it, you risk failure cause supposedly the clean fluid will remove varnish, other junk, and possibly worn friction material.
So with unknown previous service, which is taking the greater risk? I got this car with 261,000 miles.

As far as varnish is concerned, the only ones I remember being REALLY bad about that were the ECAT units (Oh god I hated those things). Not even the wonderful Ford transmissions did that.
The 97 Acura CL has a M7ZA. Are those known to varnish up? I have not worked in the field since 1998. I was in the back rebuilding so by the time one made it to my bench, it was TOAST and needing a rebuild. For that reason I never paid much attention to the fluid and how it correlated to how bad a shape the thing was in.

So on a personal note, here is a sample of the fluid in there. It doesn’t really have a “burnt” smell (not that my sinuses work very well anyways)

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[Kenneth]

I always drain the fluid, then replace with fresh fluid. Wait a couple hundred miles, then repeat, for a total of four fill ups. Which in the Hondas that I’ve owned, was a whole case of fluid. It’s easy, and has always cured any shifting problems, that I’ve had.
Then do a drain and fill every thirty thousand miles. I’ve never had any issues afterwards. A case of genuine Honda fluid, costs around a hundred bucks, and it was money well spent. Also the method I described, is the recommended one by most of the Honda/Acura techs.

[Paul]

That fluid looks good for the mileage, most likely already been replaced once. I think its worth a drain and refill as kenneth07ex has already suggested drain refill over a period of time, that way your only adding a small quantity of the capacity of the trans at each fill so less likely to pull tons of crud out of the trans in one go. Plus I would wager your trans is in pretty good order going by that fluid and likely isn’t that full of crud anyway.

[zero]

[quote=”Kenneth07ex” post=125345]the method I described, is the recommended one by most of the Honda/Acura techs.[/quote]

Actually Honda does NOT recommend any sort of mechanical fluid exchange or flush as it is commonly called.

There’s no pan to drop on any Honda that’s ever come into my bay (dealership) just a drain plug. depending on the transmission you’ll get about 3 liters out of it, I think most of the capacities are in the 8-12 liter range. Again depending on the exact transmission etc. Any quality aftermarket ATF should cover the requirements of your model, the individual fluid manufacturers website should have the information. The only time you have to be weary is newer AWD vehicles because in most cases the differential shares transmission fluid, viscous coupler, yada, yada.

Just make sure you replace the gasket/washer on the drain plug after each use.

[Author]

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